Developers of various electronic devices demand size reduction of electronic components. Technologies are also needed to make capacitors thinner. Among technologies that make capacitors thinner, technologies are considered that can make a dielectric layer of a capacitor thin. A typical example of this technology is a capacitor on which a thin dielectric layer is formed using a thin film formation technology such as a sputtering method. This capacitor is called a thin film capacitor. A structure of a thin film capacitor can be easily understood by an example of JP2002-26266 (A). A thin film capacitor shown by JP2002-26266 (A) is a structure in which a substrate, a first electrode layer, a dielectric layer, and a second electrode layer are layered, in this order.
As a dielectric layer of a thin film capacitor is made thinner, problems arise such as (1) an increase in a leak current, (2) deterioration of a withstand voltage, and (3) an increase in the number of short-circuit failures due to an increase in defects of the dielectric layer. The “defects” of (3) are portions different from a structure in which the dielectric is continuous, which exist on a surface of or inside the dielectric layer. Examples of defects include foreign objects, cracks, pinholes, or the like on a surface of or inside the dielectric layer. In a dielectric layer constituted by inorganic dielectric crystals, a crystal grain boundary is also a defect. There are cases that if a dielectric layer is made thinner, the crystal grain boundary may go through the dielectric layer.
Many researchers have tried to resolve the above-mentioned problems. JP2002-26266 (A) shows the idea that problems such as generation of short-circuit failures, an increase in a leak current, and deterioration of a withstand voltage occur due to pinhole portions and crystal grain boundaries of a dielectric layer. JP2002-26266 (A) also discloses a technology that forms an insulating layer, by oxidizing a material that constitutes a first electrode layer, between (i) the pinhole portion of the dielectric layer or the crystal grain boundary and (ii) the first electrode layer. JP2002-185148 (A) discloses a technology that repairs a missing portion of an insulating layer or the like of a multi-layer wiring substrate that is formed by layering an insulating layer or a low dielectric layer on a conductive pattern of a lower layer, and layering a conductive pattern of an upper layer on the insulating layer or the like. In this technology, after the insulating layer or the like is formed, an insulating material such as an epoxy resin or the like is caused to adhere to the missing portion of the insulating layer or the like by using an electrodeposition method in which the conductive pattern of the lower layer is used as one of electrodes. JP2008-160040 (A) discloses a technology that forms a resin insulating material in a pinhole portion of a dielectric layer, using an electrophoresis method. Meanwhile, JP2004-165596 (A) discloses a technology that improves a withstand voltage of a thin film capacitor by improving a material and/or a structure of a dielectric layer.